As is well known, building structures are subject to numerous external kinetic forces from seismic movement, wind, thermal variations, and the like. To accommodate these forces, many building are provided with expansion joints which permit relative movement of the various wall and roof sections of the structure. Such expansion joints are capable of accommodating both functional movements, such as thermal expansion and contraction and the swaying of the structure caused by the wind, and seismic movements caused by shifts in the underlying terrain.
For both functional and aesthetic reasons, it is advantageous to seal expansion joints in such kinetically designed structures. An expansion joint seal system must serve a number of functions: it must normal joint movement, it must provide a weather tight joint, it must maintain the integrity of the joint seal during seismic movements, and it should present an aesthetically acceptable appearance. In addition, when the expansion joint is located in a roof or other horizontal plane exposed to the elements, the horizontal seal system should also resist the accumulation of water and, preferaby, deflect water away from the joint.
A typical device for sealing an expansion joint between adjacent dynamic structures in a roof or other like horizontal application comprises a convex elastomeric cover. Opposing lateral portions of the cover are secured to the adjacent dynamic structures such that the cover spans the joint between the structures to prevent water and debris from penetrating the joint. Such covers are commonly arcuate or shaped like an inverted "V", but they can be of any appropriate convex shape. A conventional manner of securing the cover to the adjacent structures is to provide a pair of elongated metal frames mounted to mutually facing portions of the structures. Locking tabs formed on lateral portions of the convex joint cover are received in longitudinal locking channels is the metal frame members to fasten the joint cover to the frames.
Under normal operation of the joint, as the joint, as the joint opens, such as would occur in response to strong winds or upon thermal contraction of the adjacent structures, the convex cover will tend to flatten out as its lateral edges, anchored to opposing sides of the joint, are pulled apart. Conversely, as the joint closes, the convex cover will tend to bow upwardly as its lateral edges are brought closer together. At all times, however, the cover spans the expansion joint between the adjacent structures to seal the joint against water and debris.
The typical prior art expansion joint seal can optionally include a secondary or seismic seal mounted within the joint beneath the convex cover. The lateral edges of this seismic seal are conventionally secured to the same frame members which retain the convex cover. The seismic seal is capable of accommodating a broader range of movement than the convex cover without becoming ruptured or dislodged. Thus, in the event that serve movement of the adjacent structures causes the joint to open further than the convex cover can accommodate, such as would occur in the event of an earthquake, the seismic seal will maintain the integrity of the expansion joint seal.
A problem associated with prior art horizontal expansion joint seals concerns terminating the convex cover in such a manner that the end of the joint is sealed against water and debris without obstructing normal joint movement. Often, the convex covers of prior art horizontal expansion joint systems have been left open at their ends, permitting normal joint movement but allowing water and debris to penetrate the joint. Other times, the end of the cover has been crudely covered by a transverse wall, which either impeded normal joint operation or separated from the cover under normal joint movement, again compromising the integrity of the seal.
Thus, there is a need to provide an improved seal system for horizontal expansion joints wherein the ends of the joint system are sealed against water and debris, while permitting normal joint movement.
There is a further need to provide an apparatus for sealing the ends of existing seal systems for horizontal expansion joints against water and debris while permitting normal joint movement.
There is still a further need to provide an end cover for a horizontal seal system which presents an aesthetically pleasing appearance.